In wireless or cellular communications systems, a network of cells may be defined by spaced towers having antennas directed in particular directions. Usually, several antennas are mounted at or near the tops of the towers, while associated electronics, such as radio frequency (RF) power amplifiers, radios, and/or low noise amplifiers (LNAs), etc., are contained within small housings, or huts, located near the bases of the towers. Such an arrangement of a tower, antennas, and associated electronics are often referred to as a “base terminal station” (BTS) or “cell site”. Moreover, some cell sites employ the same tower structure for a plurality of operators, such as AT&T, Sprint, Verizon, etc., utilizing multiple frequencies and/or applications.
Predominantly, cell sites utilize multiple coaxial cables that traverse the tower, connecting the electronics to the antennas. Unfortunately, such coaxial cables are typically very lossy, a significant amount of the power in signals being conducted by cables being dissipated or “lost” between the electronics and the antennas. For example, for transmitting a signal, a RF power amplifier may be located at the base of the tower, while the associated antenna is at the top of the tower, a coaxial cable coupling the two. Consequently, for a given amount of power delivered to the antenna, the RF power amplifier must have the additional gain necessary to overcome any losses inherent in the coaxial cable. Often, a RF power amplifier having the additional output power necessary is not realizable or is more expensive, thereby increasing the costs of the cell site, or, at a minimum, the performance of an existing amplifier may be reduced.
Conversely, in receiving a signal, the power incident on an antenna at the top of the tower is coupled, via a coaxial cable, to a radio or LNA at the base of the tower. Typically, received signals are relatively low in power, and are further reduced in power by conducting through the coaxial cable. Moreover, noise, received by such coaxial cables, may reduce in the signal-to-noise ratio (S/N). One approach to improving the S/N is to locate amplifiers, typically LNAs, at the tops of the towers to overcome the noise problems associated with the coaxial cables. However, the implementation and/or maintenance of tower top LNAs can be expensive, and the mounting and installation of LNAs somewhat difficult.
There is a need to provide a method and apparatus for coupling antennas located proximate the top of a support structure with electronics located proximate the base of the support structure to overcome losses typically associated with coaxial cables.